Women who are diagnosed with gestational diabetes are at increased risk for developing prediabetes and type 2 diabetes. To date, there have been few interdisciplinary interventions that target predominantly ethnic minority low-income women diagnosed with gestational diabetes. Programs are needed that intervene in the prenatal period to teach women the importance of breastfeeding to improve metabolic control and infant health, and that continue after birth to promote improved nutrition, exercise patterns, and weight loss. Using a two-group, repeated measures experimental design, this proposed study will test a 14-week intensive intervention on the benefits of breastfeeding, understanding gestational diabetes and risk of progression to prediabetes and type 2 diabetes, nutrition and exercise education, coping skills training, and physical activity (Phase I) and 3 months of continued monthly contact (Phase II) to help overweight women diagnosed with gestational diabetes improve metabolic, clinical, weight, adiposity, health behaviors and self- efficacy. Trends in breastfeeding duration and intensity, maternal infant feeding behavior, and infant growth trajectory (weight-for-length) will also be measured. Women will be inducted from The University of North Carolina Health Care Maternal Fetal Medicine clinic and the Wake County Human Services clinic. A total of 100 African American, bilingual Hispanic, and non-Hispanic White women diagnosed with gestational diabetes will be inducted and randomized by site to either the experimental or wait-list control group. Data will be collected at T1 (Baseline at 25-32 weeks pregnant), T2 (6 weeks postpartum), T3 (4 months postpartum and completion of Phase I), T4 (7 months postpartum and completion of Phase II), and T5 (10 months postpartum and after 3 months on their own). Primary maternal outcomes will include fasting blood glucose and weight (BMI). Secondary maternal outcomes will include clinical outcomes (oral glucose tolerance test, insulin levels, Homeostasis Model Assessment calculation, Hemoglobin A1c, complete lipid panel, and blood pressure); adiposity (waist circumference, triceps and subscapular skin folds); health behaviors (Health Promoting Lifestyle Profile II, Adult Health Behavior Survey, and Accelerometry for 7 days); and self-efficacy (Eating Self-Efficacy, Exercise Self-Efficacy Scale, and Breastfeeding Self-Efficacy Scale). Infant outcomes will include data on weight status (weight-for-length) and breastfeeding (weeks until stopped breastfeeding, weeks exclusively breastfed, and intensity of breastfeeding). Data analysis will include analysis of field notes, post-intervention interviews, and recruitment and retention efforts. Linear mixed- effects random coefficients models will be constructed to measure the effects of the intervention compared to the wait-list control group. Increasing breastfeeding and decreasing overweight in postpartum women who were diagnosed with gestational diabetes may both improve maternal glucose homeostasis and weight and stabilize infant growth trajectory, reducing the burden of metabolic disease across two generations. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because the prevalence of gestational diabetes and overweight and obesity is increasing. This project will assess the acceptability of a prenatal and postpartum intervention for women diagnosed with GDM. Our results will provide data for a planned randomized controlled trial to test the effectiveness of a lifestyle intervention to reduce the burden of metabolic disease among parous women and improve their infant's outcomes.